Make and Break Your Own Hand: A Review of Hand Anatomy and Common Injuries

Audience The target audience for this small group session is emergency medicine residents, primarily for use in didactic conference. This session can also be utilized with medical students, or faculty looking to review relevant hand anatomy and common injuries. Introduction Three-dimensional (3D) printing is an emerging technology that has the ability to produce highly accurate anatomic, cellular and medical device models. Limited research has shown promise in teaching anatomy,1 congenital heart disease2 and surgical pre-operative planning.3 Despite this potential, there is sparse evidence of 3D printing emergency medicine residency education. The Model of Clinical Practice of Emergency Medicine specifies content for American Board of Emergency Medicine certification and requires proficiency in a wide breadth of medical topics including upper extremity and hand injuries.4 The concepts of hand anatomy and function rely heavily on understanding spatial relationships between bones, tendons and ligaments. The instructional strategy of working with 3D printed hand models aligns with these learning goals. This project seeks to directly incorporate 3D printing into the orthopedic curriculum of emergency medicine residents during a required weekly didactic educational session. Educational Objectives By the end of this session, learners should be able to name and identify all bones of the hand; arrange and construct an anatomically correct bony model of the hand; build functional phalangeal flexor and extensor tendon complexes onto a bony hand model; describe the mechanism of injury, exam findings, and management of the tendon injuries Jersey finger, Mallet finger, and central slip rupture; draw/recreate injury patterns on a bony hand model; and describe the mechanism of injury, exam findings, imaging findings, and management of scapholunate dissociation, perilunate dislocation and lunate dislocation, Bennett’s fracture, Rolando fracture, Boxer’s fracture and scaphoid. Educational Methods This session was delivered in a small group session which utilized educational methods grounded in constructivist learning such as complex problem-solving, social negotiation, and spatial learning. Research Methods Verbal feedback was obtained after the session. Results Overall learners found the session engaging, interactive, and especially useful in demonstrating relevant hand anatomy and injuries. Learners felt that hands-on experience with the hand models reinforced knowledge and helped them better identify injuries in a spatial fashion. Topics Extremity bony trauma, dislocations/subluxations, tendon injuries.


Other Material Preparation
Prepare the elastic cord by cutting six-30cm length strands and two-20cm length strands. The cords have been color coded in the following instructions as a visual aid for this activity. If desired, each cord may be color-coded using markers. Also, if needed, carpal bone holes may be color-coded to match corresponding color of cord.
Cut blue ribbon into two 5cm length sections. With one blue ribbon section, cut a vertical 1cm line into the center of the ribbon. In the other blue ribbon, cut one end of the ribbon 2.5cm, vertically to create two "tails" at the end of the ribbon. Cut red ribbon into two 5cm sections.

Results and tips for successful implementation:
This session is best implemented when instructors have adequately prepped learning materials for the session. In terms of the 3D printing, the above session is a detailed tutorial on how to approach 3D printing the model and can be easily followed by those with minimal experience with the technology. If there is access to a maker's space or technologist who is facile with the technology, we recommend utilizing these resources for the 3D printing process.
In terms of pre-session preparation, we recommend that instructors attempt construction of the hand model prior to the session. This not only provides insight into the learner process but can identify rate limiting steps that can be expedited in the session. For example, in our session, learners were having trouble threading elastic cord through the bone models due to small pieces of material in the threading holes. Had we attempted to build these hands ahead of time, we could have cleared the openings and prevented this frustrating step.
We also recommend having all material organized and labeled prior to the session. As discussed below, colored elastic cords were immensely helpful in orienting our learners in how to articulate the model. We pre-cut and then colored these items with permanent marker prior to the session. An additional step that could have led to more efficient model building would be to color the model bone elastic cord holes with the same color that matched the color of elastic cords being used. We also precut ribbon that was used to model tendons, and packed each complete model in a separate bag for learners. Each bag contained the bone models, elastic cord, ribbon, tape, a permanent marker, and a threading tool.
We implemented this session on a group of 24 emergency medicine residents and medical students rotating on our emergency medicine clerkship. Verbal feedback was obtained after the session. Overall learners found the session engaging, interactive and especially useful in demonstrating relevant hand anatomy and images. Time was a significant limitation in our session. We had the session planned for 90 minutes, but most teams were unable to complete all aspects of the session. This meant that some teams were unable to even begin the injury matrix exercise at the end of the session. The most rate limiting step was the hand articulation portion, where learners had difficulty finding the correct orifices that corresponded to the various elastic cords. As discussed above, color coordinated cords and markings on the bone model could decrease the time needed building the model.
Pre-building models could have been a feasible alternative to improve the timing problems with this session. Learners could be given disarticulated bones to arrange in anatomical order, but then skip the building step and be given the pre-built model to have adequate time to explore tendon function/injuries and bony dislocations and fractures.
Verbal feedback indicated that building hand tendon models was useful for constructing knowledge in tendon function and injuries in learners, but the rudimentary nature of these models made it difficult to have the tendons "function" as hoped.
When residents would pull on the tendon complex created, often times the model would just bend the finger in a nonanatomic way. This could be mitigated by bracing the hand model and allowing only the finger to move. Despite not being able to fully recreate anatomical movement with these models, they were still helpful in having learners visualize how flexor/extensor tendons and hand bones interact in a spatial manner.
Finally, the injury matrix allowed learners to synthesize information from pre-reading and the hand building session. The matrix does take significant time to complete, and we did not have a group complete this component of the session. We recommend taking advantage of the collaborative nature of Google Docs and assigning specific rows of the matrix to specific teams. This would allow learners to dive more deeply into 1-2 specific topics and provides a complete matrix that could be used by all learners for future reference.

Pearls:
Learning pearls are nicely summarized in the Hand Injury Matrix that learners complete as part of this activity. Answers to this session are located in this link: https://docs.google.com/document/d/1WQ4Px2wdLf6IiitfIMny MK1jDyjTTKuT-yEItIYLZeI/edit?usp=sharing 1. The Pre-Quiz: a. Arrange bones in correct anatomical order (palm/volar orientation) on a blank sheet of paper.
Note that due to the shape of the wrist bones, the wrist bones will not lay in proper anatomical position. b. Identify and label the three bone groups of the hand.  i. First, tie a large knot at the end of each cord before threading (knots must be larger than the 2.0mm distal phalangeal bone holes). This knot will anchor the cord within the distal phalanx. ii. Thumb (white): distal phalanx→ proximal phalanx→ metacarpal→ trapezium (articular surface) → scaphoid (palmar hole) → lunate (palmar hole). iii. Index (red): distal phalanx→ middle phalanx→ proximal phalanx→ metacarpal→ trapezoid (articular surface) → scaphoid (dorsal holes) → lunate (dorsal holes).